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Subject: SPACE Digest V11 #89

SPACE Digest                                      Volume 11 : Issue 89

Today's Topics:
             Outerspace Economics
               long-term Venus landers
         Comments to recent postings (short)
       Re: NASA Headline News for 02/26/90 (Forwarded)
        Re: New private home satellite network
Aeronautics/Exploration/Technology offices merger completed (Forwarded)
            Challenger Last Words
          Re: Spacecraft drives and fuel efficiency
----------------------------------------------------------------------

Date: Mon, 26 Feb 1990 13:03 EDT
From: Rodney Baker <[e-mail]>
Subject: Outerspace Economics
X-Envelope-To: [e-mail]


I am doing a research paper on the economic advantages of space exploration.
If any one knows of any really good materials I could use regarding minning,
space stations, colonies,..., I would GREATLY
appreciate it if you could E-Mail me the titles of any books, lectures,
articles, etc. that you could think of!

Thanks in advance!

                                             Rodney Baker (HOTROD@JHUVM)
                                             Johns Hopkins University

------------------------------

Date: Wed, 28 Feb 90 20:59:27 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: long-term Venus landers


>From: @decwrl.dec.com  (N = R*fgfpneflfifaL 20-Feb-1990 1302)
>Subject: Spacecraft on Venus

>        What would it take - in terms of alloys, etc. - for a manned
>    spacecraft to survive on the planet Venus?  Keep in mind that
>    this world contains an atmosphere of carbon dioxide and sulfuric
>    acid, an atmospheric pressure ninety times that of Earth, and
>    a surface temperature capable of melting lead.

>        No Soviet or American lander has yet survived longer than a
>    few hours on this hellish planet.  What would it take to keep
>    such a craft functioning for days and weeks, even months?  Would
>    there be any way to construct a permanent base, keeping in mind
>    that the Venusian climate cannot be changed any time soon.

>        Larry Klaes

Having thought about the matter over the past few months, I'm pretty sure
that it would not be as horribly difficult as you might think. The key is
to design a lander/rover so that almost all of the craft is able to operate
at ambient temperature and pressure. A few parts might have to be kept cool
(i.e. communications, imaging, some of the electronics), and these would have
to be actively cooled. If these sections are well insulated and don't use
much power, this might not be too difficult. Some of the electronics might be
able to operate at local temperature (for instance, vacuum tube technology,
if it can be made dense enough). The rest of the craft could be made of
solid metal and ceramic parts. Power could be supplied by a high-temperature
RTG (do thermocouples work at that temperature?) or a nuclear reactor with
a heat engine.

Possible problems:
 - Corrosion (possible) - If necessary, metal parts could be coated with
   ceramic.
 - Cooling of power source - Does convective cooling work on the surface
   of Venus?
 - Changes in physical properties of materials - At high temperatures, some
   materials are softer than normal. Electrical resistance of conductors
   changes. Magnetic materials (for motors, etc.) have different properties.
   All of these factors have to be taken into account.
 - Differential expansion - At high temperatures, some materials expand more
   than others. Materials must be carefully chosen, and dimensional tolerances
   must be adequate.

Other possibilities:
  I'm not sure, but I think temperature drops off fairly rapidly with
  altitude. With an atmosphere composed mainly of carbon dioxide, a sturdy
  balloon filled with a gas such as nitrogen (or heated CO2) should float.
  If a balloon could be used to run a tether up to an altitude at which
  the temperature is significantly lower than at the ground, this temperature
  differential could possibly be used for cooling or for power generation.
  It is possible that the craft could continue to operate from this power
  source after its internal power supply had been exhausted.

                   John Roberts
                   [e-mail]

------------------------------

Date: 28 Feb 90 20:45:54 GMT
From: [e-mail]  (SERRE GLENN)
Subject: Comments to recent postings (short)

Apoligies for posting in this way, but my time is very limited (I work for a
company that launches rockets, BTW.) and I have yet to get organized with
regards to net interaction.

Response to a mention of "Ring burning" SRMs:
The Titan III and Titan IV both use segmented SRMs like those on the shuttle.
The Titan SRMs are made by United Technologies.

Response to a statement that there are no operational spacecraft except maybe
Proton:
Titan II and Titan III (now Commercial Titan) have had numerous launches, and
hundreds of copies have been built.  The Titan III series (same core vehicle,
different options) has had well over one hundred launches.  The same comments
probably apply to Delta.

Larger = more complex?
I'm still not convinced.  The original question was not whether SCALING a
design creates more stress and complexity, but whether a BIGGER design (i.e.
more payload, larger cargo bay) is more complex.  Certainly the proportions of
the vehicle might have to change (beams of larger cross-section in compar-
ison to the tank cross-section) and the *manufacturing* problems might be
harder, but that doesn't necessarily imply a more complex design.
In particular, there would be no intrinsinc reason to increase things like
chamber pressure or turbine speed.
Note that this is not a request for more net discussion, but a dissent from
the latest and longest posting on the subject.

Antimatter for launch vehicles:
Probably the simplest way to use antimatter to power a launch vehicle would
be to inject a very small stream of it into the combustion chamber of a rocket
and use the matter-antimatter reaction to heat propellent instead of using
a chemical reaction to do so.  How to inject and control the antimatter is,
of course, an open question :-).

Glenn Serre
[e-mail]

------------------------------

Date: 27 Feb 90 16:46:57 GMT
From: cs.utexas.edu!romp!auschs!awdprime!larch.uucp![e-mail]  (Christopher F. Broadbent)
Subject: Re: NASA Headline News for 02/26/90 (Forwarded)


In article <[e-mail]> [e-mail] (Peter E. Yee) writes:
>-----------------------------------------------------------------
>Monday, February 26, 1990                     Audio: 202/755-1788
>-----------------------------------------------------------------
>This is NASA Headline News for Monday, February 26.....
>
>...............[other text deleted]
>
>Using a NASA/JPL Deep Space Network antenna located in Madrid,
>Spain, the European Space Agency reestablished contact with the
>Italian comet probe "Giotto" last Tuesday.  Aerospace Daily says
 ^^^^^^^

>Giotto had been dormant since the March 1986 encounter with
>Halley's comet.  ESA is now preparing systems to encounter the
>comet Grigg-Skjellerup in July 1992.
>
>...............[other text deleted]

I feel obliged to point out that the prime contractor for Giotto was
British Aerospace, with the experiments supplied by many European
countries.  The reason for the Italian name 'Giotto' is because of the
depiction of a comet in one of his paintings.  It is beleived that
this comet was, in fact, Halley.

I shall return to lurker mode now.

Chris.

------------------------------

Date: 27 Feb 90 23:41:59 GMT
From: mcgill-vision!quiche![e-mail]  (Ronald BODKIN)
Subject: Re: New private home satellite network

In article <[e-mail]> [e-mail] (Brad Templeton) writes:
[about NBC's satellite network and private enterprises launching satellites
for this, along with reaction on Earth]
>Of course, space in geosync orbit is limited.  There may be one light second
>of circumference out there, but it's really only 2PI radians, and in
>particular, much less within view of North America.  This is a resource
>that will soon become scarce.  I wonder what people will do about it?
    A fascinating question -- and one which the international community
is most embarrasingly backward in.  As I read it international law currently
tries to make all non-populated space an area with little use, i.e. no way
to enforce laws (e.g. there is an agreement that no one is to govern space/
Antartica) and hence no enforcement of property rights of any kind, which is
the only successful way to handle such issues.  I imagine that this kind of
enterprise will eventually make it necessary for some reevaluation.  As for
your scenario, I personally doubt thatthe US would react very strongly
if it were launched within the confines of a small country.  But I'd bet
the CRTC would attempt to regulate it anyhow, perhaps at the demand side?
If that didn't work, who knows?  There would certainly be a lobby against
having it continue, but pirate radio stations are still operating in spite
of the efforts of the government.  And it seems very tough to jam the
signal.
        Ron
p.s. international law frowns on space weaponry, including blowing up
satellites, but it WOULD be interesting to see how the US would
destroy it if indeed they did.

------------------------------

Date: 28 Feb 90 22:59:55 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Aeronautics/Exploration/Technology offices merger completed (Forwarded)

[And you thought this only happened on Wall Street! -PEY]

David W. Garrett
Headquarters, Washington, D.C.                  February 28, 1990


RELEASE:  90-32

AERONAUTICS/EXPLORATION/TECHNOLOGY OFFICES MERGER COMPLETED


     NASA Administrator Richard H. Truly announced today the
creation of the Office of Aeronautics, Exploration and Technology
(OAET).  This formalizes the merger of two previous NASA offices,
the Office of Aeronautics and Space Technology and the Office of
Exploration.

     On Dec. 21, 1989, Truly stated his intention to merge the
two offices in order to continue the analysis of exploration
mission alternatives and to begin the actual pursuit of
innovative technologies.  At that time, he said the two efforts
were closely related and that they should proceed under a strong
central management.  Also, he emphasized that in no way would the
consolidation of the two offices diminish the agency's dedication
to aeronautical research.

     The OAET will be headed by NASA Associate Administrator
Arnold D. Aldrich.

     In approving the consolidation, Truly said, "This office
will provide the planning, direction and technology, as well as
manage the assessment of concepts and technology for human
exploration beyond Earth orbit into the solar system.  I view
this as a major step in streamlining the management arrangement
that will combine cutting-edge technologies with studies of
future space and aeronautics missions."

------------------------------

Date: 28 Feb 90 06:13:45 GMT
From: cs.utexas.edu!usc!iris.usc.edu![e-mail]  (Steve Robiner)
Subject: Challenger Last Words

Does anyone out there know if the last minutes of the Challenger
flight recorder were ever released.  If so, where can I get a copy
or transcript.

About a month or so after the crash, I heard that the NYT was suing
NASA for the tape, but that's the last I heard of it.

I now see accounts of the crash where NASA officials publicly indicate the
crew died at impact (with the ocean) and not during the explosion as originally
speculated.

=Steve=

------------------------------

Date: 28 Feb 90 23:31:18 GMT
From: elroy.jpl.nasa.gov!usc!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Tim Maroney) writes:
>
>I think the antimatter should be produced in lunar factories and should
>never enter the atmosphere regardless.  It's just too dangerous to the
>ecosystem, and the containment is intrinsically iffy.
>
   I don't know about this. It is a very powerful explosive, but it is also
relatively clean. More on this later. Hydrocarbons are much more dangerous
to the environment, since they stick around and contaminate things, and we
allow them in the atmosphere. If containment failed on an antimatter
container, it would explode. It would deposit some energy as gamma rays,
and sundry other particles, but that would be the end of it. An equal
energy release from, say, burning automobile tires, would be a lot more
damaging to the local ecosystem.

>In article <[e-mail]> [e-mail] (Henry Spencer)
>writes:
>>It all ends up as gamma rays (or stray
>>electrons and positrons) eventually, but you want that happening as far
>>away as possible, a kilometer or so back in the exhaust jet when the muons
>>decay.  There *are* a lot of gamma rays even so, enough to be a problem.
>
>Yeah, and it's a little tricky to outrun them... :-)
>
   Yes, but maybe you don't have to outrun them.
   A pure photon drive, or one whose reaction mass consists just of the
pions, gammas, electrons, and muons of the annihilation reaction would be
ideal, but is a very long way off. There are less efficient ways to do
this. The first antimatter drive will probably inject the energy from an
annihilation reaction into a vessel of water. The water would be boiled,
and atomised, and the superheated oxygen and hydrogen plasma would stream
out a nozzle at the back. Perhaps liquid hydrogen would be more efficient,
but water is safer, at least in atmosphere, and more convenient to handle
because it doesn't require cryogenics.
   The water tank technique has a few strong points. The penetration depth
of gamma rays in water at the wavelengths involved in an annihilation
reaction is on the scale of centimetres to decimetres. A few metres of
water between the reaction vessel and the electronics and crew would block
essentially all the gammas. Charged pions and electrons don't penetrate
very far in water either, they deposit the energy as heat, though the pion
can lose some energy to neutrinos and muons. Muons have a high mass to
charge ratio and don't interact via the strong interaction, and hence have
a very high penetrating power. For this reason the are not very effective
against electronics or living matter. A couple of muons have probably
passed through your body since you started reading this article, the number
depending on your elevation.
   So, a tank of water should shield all the sensitive components of a
space craft from the energetic particles leaving the annihilation region.

>>You may not have noticed :-), but all existing space propulsion systems
>>fry the immediate vicinity when they take off...
>
>Hmm.  How much antimatter would you have to annihilate to escape the
>gravity well?  Micrograms per launch?  I tend to think it would "fry"
>the immediate vicinity a little worse than extreme heat does.  Wouldn't
>there be a good deal of residual radiation, especially after multiple
>launches of large craft?  Current launch pads are reusable pretty
>quickly, and the atmospheric pollution is insignificant.
>
   I think a NASA study showed something like 1mg to launch the shuttle
using a reaction mass tank such as I described above.
   The launch pad would probably be more badly treated by such a launch
than by a pure chemical launch, primarily by the potentially higher heat,
and the high energy electrons which can break chemical bonds.
   There should be negligible residual radiation. There is a big difference
between nuclear reactions and annihilation reactions. Pions, muons,
electrons, neutrinos, and gammas are all non-activating. Concrete is
composed primarily of light elements, and shattering light elemental nuclei
with high energy particles results in stable elements. Neutrons could
activate light nuclei, but the only neutrons available in the annihilation
reaction would come from shattering nuclei. If the reaction vessel is such
that antihydrogen reacts with hydrogen, there shouldn't be much in the way
of flying neutrons. Perhaps the magnetic containment of the antimatter
could have walls lined with frozen hydrogen, so that when the containment
is released, the hydrogen and antihydrogen reaction is dominant. You'd have
hundreds of small vessels like this, which you would detonate sequentially
to provide some semblance of steady thrust.
   Atmospheric pollution in current launchers is not really insignificant.
Would you inhale the exhaust from the SRBs if it were bottled and cooled?
   An antimatter engine with water reaction mass would produce a reaction
jet of plasma which would be dangerous. The radiation, which is not
persistent, would be worrisome only in places already decidedly unhealthy
because of the extreme heat of the reaction jet (it is unsafe to stand
directly beneath any rocket at take-off). Pollution would result from
chemical reactions in the atmosphere under the flame, primarily reaction of
nitrogen and oxygen to make nitrous oxides. The rocket would be a
detectable muon source at close range, but as I mentioned above, muons are
relatively benign.

>Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, [e-mail]


--
 Christopher Neufeld....Just a graduate student  |
 [e-mail]              | "Vulcan has no moon."
 [e-mail]                    | "I'm not surprised!"
 "Don't edit reality for the sake of simplicity" |

------------------------------

End of SPACE Digest V11 #89
*******************